A high-pressure cylinder coupled with solar light and heat and a method for providing heat

Abstract

The application provides a high-pressure cylinder and medium-pressure cylinder coupled with solar light heat and a heat supply system and method, and the system comprises a light heat power station, a molten salt heat exchange station and a thermal power plant subsystem; the light heat power station is used for collecting solar heat and delivering the heat to the molten salt heat exchange station; the molten salt heat exchange station is used for heating cold reheat steam to generate hot reheat steam and delivering the hot reheat steam to the thermal power plant subsystem; the thermal power plant subsystem is used for providing steam and electric energy to users; wherein the thermal power plant subsystem comprises a boiler, a second high-pressure cylinder, a first high-pressure cylinder, a first medium-pressure cylinder, a second medium-pressure cylinder, a low-pressure cylinder and a generator, and the boiler, the second high-pressure cylinder, the first high-pressure cylinder, the first medium-pressure cylinder, the second medium-pressure cylinder, the low-pressure cylinder and the generator are sequentially connected. The technical scheme provided by the application is coupled with solar energy by dividing the high-pressure cylinder and the medium-pressure cylinder, and the solar heat is efficiently used to replace part of the coal consumption in the boiler, so that energy saving and emission reduction and energy cascade utilization are realized.

Description

Technical Field

[0001] This application relates to the field of energy utilization, and in particular to a heating system and method of a high- and medium-pressure distribution cylinder coupled with solar thermal energy. Background Technology

[0002] The proportion of renewable energy sources such as wind and solar power is becoming increasingly significant. However, these renewable energy sources are intermittent and volatile, posing new challenges to the power grid. Cogeneration (CHP) units, while providing industrial steam, also frequently participate in peak shaving, especially during deep peak shaving. The pressure of the original industrial steam extraction points cannot meet the industrial steam demand, necessitating a switch to higher extraction pressure points. For example, thermal power units use main steam desuperheating and depressurization under low-load conditions to meet the parameter requirements of high-pressure industrial steam, and hot reheat steam desuperheating and depressurization to meet the parameter requirements of low-pressure industrial steam. These conventional low-load steam source switching methods result in poor unit thermal economy and significantly increased coal consumption. Therefore, developing a new, efficient, flexible, and energy-cascaded cogeneration technology that meets the unit's peak shaving needs for large-scale steam supply is urgently needed. Summary of the Invention

[0003] This application provides a heating system and method for a high- and medium-pressure split cylinder coupled with solar thermal energy, in order to at least solve the technical problems of poor economic efficiency caused by the inability of existing steam-supply cogeneration technology to save energy and reduce emissions and the failure to utilize energy in a cascade manner.

[0004] The first aspect of this application proposes a heating system with a high- and medium-pressure sub-cylinder coupled with solar thermal power, including: a solar thermal power plant, a molten salt heat exchange station, and a thermal power plant subsystem;

[0005] The solar thermal power plant is used to collect solar heat and transport the heat to the molten salt heat exchange station;

[0006] The molten salt heat exchange station is used to heat cold reheat steam to generate hot reheat steam, and then transport the hot reheat steam to the power plant subsystem.

[0007] The thermal power plant subsystem is used to provide steam and electricity to users;

[0008] The thermal power plant subsystem includes a boiler, a second high-pressure cylinder, a first high-pressure cylinder, a first intermediate-pressure cylinder, a second intermediate-pressure cylinder, a low-pressure cylinder, and a generator, which are connected in sequence.

[0009] Preferably, the molten salt heat exchange station heats the cold reheat steam to generate hot reheat steam, and then delivers the hot reheat steam to the first intermediate pressure cylinder;

[0010] The boiler is used to heat condensate to generate steam and deliver the steam to the first high-pressure cylinder.

[0011] Furthermore, a first connecting pipe is provided between the second high-pressure cylinder and the first high-pressure cylinder;

[0012] A second connecting pipe is provided between the first intermediate pressure cylinder and the second intermediate pressure cylinder;

[0013] A third connecting pipe is provided between the second intermediate pressure cylinder and the low pressure cylinder.

[0014] Furthermore, the thermal power plant subsystem also includes: a high-pressure industrial steam supply header and a medium-pressure industrial steam supply header;

[0015] The high-pressure industrial steam supply header is connected to the first connecting pipe and the outlet of the second high-pressure cylinder, respectively.

[0016] The medium-pressure industrial steam supply main pipe is connected to the second connecting pipe and the third connecting pipe, respectively.

[0017] Furthermore, the thermal power plant subsystem also includes: multiple sealed butterfly valves;

[0018] The high-pressure industrial steam supply main pipe is connected to the first connecting pipe and the outlet of the second high-pressure cylinder through the sealing butterfly valve.

[0019] The medium-pressure industrial steam supply main pipe is connected to the second connecting pipe and the third connecting pipe respectively through a sealed butterfly valve;

[0020] The sealing butterfly valve is installed between the input end of the molten salt heat exchange station and the output end of the second high-pressure cylinder.

[0021] Furthermore, when high-pressure steam is required, it is determined whether the unit load in the thermal power plant subsystem is less than a preset first load value. If so, the sealing butterfly valve connected to the first connecting pipe is opened, and the sealing butterfly valve connected to the second high-pressure cylinder is closed. High-pressure steam is then provided to the user using the extraction steam from the second high-pressure cylinder and the first high-pressure cylinder. Otherwise, the sealing butterfly valve connected to the second high-pressure cylinder is opened, and the sealing butterfly valve connected to the first connecting pipe is closed. Steam is then provided to the user using the cold re-extraction steam discharged from the second high-pressure cylinder.

[0022] And / or, when medium-pressure steam or low-pressure steam is required, determine whether the unit load in the thermal power plant subsystem is less than a preset second load value. If so, open the sealing butterfly valve connected to the second connecting pipe and close the sealing butterfly valve connected to the third connecting pipe, and use the extracted steam in the first and second medium-pressure cylinders to provide medium-pressure steam or low-pressure steam to the user; otherwise, open the sealing butterfly valve connected to the third connecting pipe and close the sealing butterfly valve connected to the second connecting pipe, and use the cold re-extraction steam discharged from the second medium-pressure cylinder to provide medium-pressure steam or low-pressure steam to the user.

[0023] Furthermore, the thermal power plant subsystem also includes: condenser, condensate pump, and unit regenerative subsystem;

[0024] The condenser is connected to the low-pressure cylinder, the condensate pump, and the unit's regenerative subsystem, respectively.

[0025] The unit's regenerative subsystem is connected to the boiler, the second high-pressure cylinder, the first high-pressure cylinder, the first intermediate-pressure cylinder, the second intermediate-pressure cylinder, the low-pressure cylinder, the condenser, and the condensate pump, respectively.

[0026] Preferably, the molten salt heat exchange station includes: a molten salt heat exchanger, a temperature gradient layer, and a main heat exchanger;

[0027] The inclined temperature layer is connected to the molten salt heat exchanger;

[0028] The molten salt heat exchanger is connected in parallel with the main heat exchanger.

[0029] Preferably, the solar thermal power plant includes: a heliostat and a solar collector tower;

[0030] The solar collector tower is connected to the molten salt heat exchange station.

[0031] The second aspect of this application provides a heating method for a high- and medium-pressure split-type cylinder coupled with solar thermal energy, comprising:

[0032] Solar thermal power plants collect solar heat and then transfer the heat to molten salt heat exchange stations.

[0033] Based on the molten salt heat exchange station, and using the heat energy delivered by the solar thermal power plant to heat the cold resteam to generate hot resteam, the hot resteam is then delivered to the thermal power plant subsystem.

[0034] The thermal power plant subsystem provides steam and electricity to users based on the heat resteam.

[0035] The technical solutions provided by the embodiments of this application bring at least the following beneficial effects:

[0036] This application proposes a heating system and method for a high- and medium-pressure cylinder coupled with solar thermal energy. The system includes a solar thermal power plant, a molten salt heat exchange station, and a thermal power plant subsystem. The solar thermal power plant collects solar heat and transmits it to the molten salt heat exchange station. The molten salt heat exchange station heats cold reheat steam to generate hot reheat steam and transmits it to the thermal power plant subsystem. The thermal power plant subsystem provides steam and electricity to users. The thermal power plant subsystem includes a boiler, a second high-pressure cylinder, a first high-pressure cylinder, a first medium-pressure cylinder, a second medium-pressure cylinder, a low-pressure cylinder, and a generator, which are connected sequentially. The technical solution proposed in this application utilizes separate high-pressure and medium-pressure cylinders and combines them with solar energy to efficiently utilize solar heat to replace part of the coal consumption in the boiler, achieving energy conservation, emission reduction, and energy cascade utilization.

[0037] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0038] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0039] Figure 1 This is a structural diagram of a high- and medium-pressure split-cylinder heating system coupled with solar thermal energy, according to an embodiment of this application.

[0040] Figure 2 This is a detailed schematic diagram of a high- and medium-pressure distribution cylinder heating system coupled with solar thermal energy, according to an embodiment of this application.

[0041] Figure 3 This is a flowchart illustrating a heating method using a high- and medium-pressure split cylinder coupled with solar thermal energy, according to an embodiment of this application.

[0042] Figure Labels

[0043] 1. Solar thermal power plant; 2. Molten salt heat exchange station; 3. Thermal power plant subsystem; 3-1. Boiler; 3-2. Second high-pressure cylinder; 3-3. First high-pressure cylinder; 3-4. First intermediate-pressure cylinder; 3-5. Second intermediate-pressure cylinder; 3-6. Low-pressure cylinder; 3-7. Generator; 3-8. First connecting pipe; 3-9. Second connecting pipe; 3-10. Third connecting pipe; 3-11. High-pressure industrial steam supply main pipe; 3-12. Medium-pressure industrial steam supply main pipe; 3-13. Sealed butterfly valve; 3-14. Condenser; 3-15. Condensate pump; 3-16. Unit regenerative subsystem; 2-1. Molten salt heat exchanger; 2-2. Inclined temperature layer; 2-3. Main heat exchanger; 1-1. Heliostat; and 1-2. Solar collector tower. Detailed Implementation

[0044] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0045] This application proposes a heating system and method for a high- and medium-pressure cylinder coupled with solar thermal energy. The system includes a solar thermal power plant, a molten salt heat exchange station, and a thermal power plant subsystem. The solar thermal power plant collects solar heat and transmits it to the molten salt heat exchange station. The molten salt heat exchange station heats cold reheat steam to generate hot reheat steam and transmits it to the thermal power plant subsystem. The thermal power plant subsystem provides steam and electricity to users. The thermal power plant subsystem includes a boiler, a second high-pressure cylinder, a first high-pressure cylinder, a first medium-pressure cylinder, a second medium-pressure cylinder, a low-pressure cylinder, and a generator, which are connected sequentially. The technical solution proposed in this application utilizes separate high-pressure and medium-pressure cylinders and combines them with solar energy to efficiently utilize solar heat to replace part of the coal consumption in the boiler, achieving energy conservation, emission reduction, and energy cascade utilization.

[0046] The following description, with reference to the accompanying drawings, describes a heating system and method of a high- and medium-pressure split cylinder coupled with solar thermal energy, according to an embodiment of this application.

[0047] Example 1

[0048] Figure 1 This is a structural diagram of a high- and medium-pressure split-cylinder heating system coupled with solar thermal energy, according to an embodiment of this application. Figure 1 As shown, the system includes: a solar thermal power plant 1, a molten salt heat exchange station 2, and a thermal power plant subsystem 3;

[0049] The solar thermal power plant 1 is used to collect solar heat and transport the heat to the molten salt heat exchange station 2;

[0050] The molten salt heat exchange station 2 is used to heat cold reheat steam to generate hot reheat steam, and then transport the hot reheat steam to the thermal power plant subsystem 3.

[0051] The thermal power plant subsystem 3 is used to provide steam and electricity to users;

[0052] The thermal power plant subsystem 3 includes: a boiler 3-1, a second high-pressure cylinder 3-2, a first high-pressure cylinder 3-3, a first intermediate-pressure cylinder 3-4, a second intermediate-pressure cylinder 3-5, a low-pressure cylinder 3-6, and a generator 3-7. The boiler 3-1, the second high-pressure cylinder 3-2, the first high-pressure cylinder 3-3, the first intermediate-pressure cylinder 3-4, the second intermediate-pressure cylinder 3-5, the low-pressure cylinder 3-6, and the generator 3-7 are connected in sequence.

[0053] It should be noted that, Figure 1 This is merely a schematic diagram of a heating system with a high-pressure, medium-pressure cylinder coupled with solar thermal energy, and does not limit the structure of the heating system in this application.

[0054] In the embodiments disclosed herein, such as Figure 2 As shown, the molten salt heat exchange station 2 heats the cold reheat steam to generate hot reheat steam, and then delivers the hot reheat steam to the first intermediate pressure cylinder 3-4;

[0055] The boiler 3-1 is used to heat condensate to generate steam and deliver the steam to the first high-pressure cylinder 3-3.

[0056] Furthermore, such as Figure 2 As shown, a first connecting pipe 3-8 is provided between the second high-pressure cylinder 3-2 and the first high-pressure cylinder 3-3;

[0057] A second connecting pipe 3-9 is provided between the first intermediate pressure cylinder 3-4 and the second intermediate pressure cylinder 3-5;

[0058] A third connecting pipe 3-10 is provided between the second medium-pressure cylinder 3-5 and the low-pressure cylinder 3-6.

[0059] Furthermore, such as Figure 2 As shown, the thermal power plant subsystem 3 also includes: high-pressure industrial steam supply header 3-11 and medium-pressure industrial steam supply header 3-12;

[0060] The high-pressure industrial steam supply header 3-11 is connected to the outlet of the first connecting pipe 3-8 and the outlet of the second high-pressure cylinder 3-2, respectively.

[0061] The medium-pressure industrial steam supply main pipe 3-12 is connected to the second connecting pipe 3-9 and the third connecting pipe 3-10, respectively.

[0062] It should be noted that, as Figure 2 As shown, the thermal power plant subsystem 3 also includes: multiple sealing butterfly valves 3-13;

[0063] The high-pressure industrial steam supply main pipe 3-11 is connected to the outlet of the first connecting pipe 3-8 and the outlet of the second high-pressure cylinder 3-2 through the sealing butterfly valve 3-13 respectively.

[0064] The medium-pressure industrial steam supply main pipe 3-12 is connected to the second connecting pipe 3-9 and the third connecting pipe 3-10 respectively through a sealing butterfly valve 3-13;

[0065] The sealing butterfly valve 3-13 is provided between the input end of the molten salt heat exchange station 2 and the output end of the second high-pressure cylinder 3-2.

[0066] In this embodiment of the disclosure, when high-pressure steam is required, it is determined whether the unit load in the thermal power plant subsystem 3 is less than a preset first load value. If so, the sealing butterfly valve 3-13 connected to the first connecting pipe 3-8 is opened, and the sealing butterfly valve 3-13 connected to the second high-pressure cylinder 3-2 is closed. High-pressure steam is then provided to the user using the extracted steam from the second high-pressure cylinder 3-2 and the first high-pressure cylinder 3-3. Otherwise, the sealing butterfly valve 3-13 connected to the second high-pressure cylinder 3-2 is opened, and the sealing butterfly valve 3-13 connected to the first connecting pipe 3-8 is closed. Steam is then provided to the user using the cold re-extraction steam discharged from the second high-pressure cylinder 3-2.

[0067] And / or, when medium-pressure steam or low-pressure steam is required, determine whether the unit load in the thermal power plant subsystem 3 is less than the preset second load value. If so, open the sealing butterfly valve 3-13 connected to the second connecting pipe 3-9 and close the sealing butterfly valve 3-13 connected to the third connecting pipe 3-10, and use the extracted steam in the first medium-pressure cylinder 3-4 and the second medium-pressure cylinder 3-5 to provide medium-pressure steam or low-pressure steam to the user; otherwise, open the sealing butterfly valve 3-13 connected to the third connecting pipe 3-10 and close the sealing butterfly valve 3-13 connected to the second connecting pipe 3-9, and use the cold re-extraction steam discharged from the second medium-pressure cylinder 3-5 to provide medium-pressure steam or low-pressure steam to the user.

[0068] It should be noted that under high unit load conditions, heating is provided by cold reheat steam extraction; after the unit load decreases, cold reheat steam cannot guarantee industrial steam supply parameters. Therefore, the first connecting pipe 3-8 is used instead of the currently commonly used main steam desuperheating and depressurization heating. The high-pressure steam supply is selected from two steam sources: (1) cold reheat steam, i.e., the exhaust steam from the second stage of the high-pressure cylinder; (2) the exhaust steam from the first stage of the high-pressure cylinder, i.e., the first connecting pipe 3-8. Currently, the heating unit uses the main steam desuperheating and depressurization heating method under low load conditions, while this paper uses the exhaust steam from the first stage of the high-pressure cylinder for heating.

[0069] During operation, condensate enters boiler 3-1 and is heated into high-temperature and high-pressure steam. It first enters the first high-pressure cylinder 3-3 of the steam turbine, and then enters the second high-pressure cylinder 3-2 to do work. The steam from the outlet of the second high-pressure cylinder 3-2 enters the main heat exchanger 2-3 to absorb heat, and the temperature rises to 566℃. Then it enters the first intermediate-pressure cylinder 3-4 and the second intermediate-pressure cylinder 3-5 to do work, and then enters the low-pressure cylinder 3-6 to do work.

[0070] Meanwhile, the high-pressure cylinder is decomposed into two parts, namely the second high-pressure cylinder 3-2 and the first high-pressure cylinder 3-3. After the main steam does work in the first high-pressure cylinder 3-3 (i.e., the first section of the high-pressure cylinder), it enters the connecting pipe between the first and second sections of the high-pressure cylinder (i.e., the first connecting pipe 3-8). The connecting pipe between the first and second sections of the high-pressure cylinder can extract steam for heating, with the second section being the second high-pressure cylinder 3-2. At the same time, combined with the cold re-extraction steam pipeline in the original power plant, a steam extraction system with dual extraction nodes is formed.

[0071] The intermediate pressure cylinder is divided into two parts. After the hot reheat steam does work in the first intermediate pressure cylinder 3-4, it enters the connecting pipe 3-9 between the first intermediate pressure cylinder 3-4 and the second intermediate pressure cylinder 3-5. The connecting pipe between the first and second intermediate pressure cylinders can extract steam for heating. At the same time, it is combined with the original intermediate pressure cylinder exhaust steam extraction to form a steam extraction system with dual extraction nodes.

[0072] In the embodiments disclosed herein, such as Figure 2 As shown, the thermal power plant subsystem 3 also includes: condenser 3-14, condensate pump 3-15, and unit regenerative subsystem 3-16;

[0073] The condenser 3-14 is connected to the low-pressure cylinder 3-6, the condensate pump 3-15, and the unit regenerative subsystem 3-16, respectively.

[0074] The unit's regenerative subsystem 3-16 is connected to the boiler 3-1, the second high-pressure cylinder 3-2, the first high-pressure cylinder 3-3, the first intermediate-pressure cylinder 3-4, the second intermediate-pressure cylinder 3-5, the low-pressure cylinder 3-6, the condenser 3-14, and the condensate pump 3-15, respectively.

[0075] Among them, such as Figure 2As shown, the unit's regenerative subsystem 3-16 includes: 3 high-pressure heaters, 1 deaerator, 1 feedwater pump, and 4 low-pressure heaters.

[0076] In the embodiments disclosed herein, such as Figure 2 As shown, the molten salt heat exchange station 2 includes: a molten salt heat exchanger 2-1, a temperature gradient layer 2-2, and a main heat exchanger 2-3;

[0077] The inclined temperature layer 2-2 is connected to the molten salt heat exchanger 2-1;

[0078] The molten salt heat exchanger 2-1 is connected in parallel with the main heat exchanger 2-3.

[0079] It should be noted that the cold reheat steam formed by the main steam at the outlet of boiler 3-1 after the second high-pressure cylinder 3-2 has completed its work is then passed through the main heat exchanger 2-3 to absorb the heat of the molten salt and form hot reheat steam. The inlet temperature of the molten salt in the main heat exchanger 2-3 can be 590℃, and the outlet temperature of the molten salt can be 350℃.

[0080] In the embodiments disclosed herein, such as Figure 2 As shown, the solar thermal power plant 1 includes: a heliostat 1-1 and a solar collector tower 1-2;

[0081] The solar collector tower 1-2 is connected to the molten salt heat exchange station 2.

[0082] It should be noted that when there is sufficient sunlight, the high-temperature molten salt in the solar collector tower 1-2 flows out, part of which goes to the molten salt heat exchanger 2-1 to heat the cold reheat steam, and part of which goes to the heat storage in the inclined temperature layer 2-2; on cloudy or rainy days and at night, the high-temperature molten salt in the molten salt tank of the inclined temperature layer 2-2 flows out to the molten salt heat exchanger 2-1 to heat the cold reheat steam.

[0083] For example, the calculation results of a conventional 350MW supercritical unit (main steam pressure 24.2MPa, main steam temperature 566℃, hot resteam temperature 566℃, back pressure set at 4.9kPa) under pure condensing conditions are shown in Table 1.

[0084] In the combined heat and power (CHP) process, the high-pressure industrial steam supply parameters are 3 MPa pressure, 250℃ temperature, and 100 t / h extraction rate; the low-pressure industrial steam supply parameters are 0.5 MPa pressure, 200℃ temperature, and 100 t / h extraction rate.

[0085] Calculation results show that at the flow rate corresponding to 100% THA pure condensation, the cold reheat steam pressure is 3.97 MPa, which can be used for heating through cold reheat extraction. However, at the flow rates corresponding to 75% THA and 50% THA, the cold reheat steam pressures are 2.96 MPa and 1.97 MPa, respectively, which are insufficient to meet the heating demand. The exhaust pressures of the first high-pressure cylinder (section 1, i.e., section 3-3) are 4.60 MPa and 3.08 MPa, respectively, which are higher than the industrial steam supply pressure, and heating can be provided through the exhaust steam from the first high-pressure cylinder.

[0086] At the flow rate corresponding to 100% THA pure condensation, the discharge pressure of the intermediate-pressure cylinder is 0.585 MPa, which can be used for heating through the discharge steam from the intermediate-pressure cylinder (the pressure is adjusted through the regulating valve of the intermediate-low pressure cylinder connecting pipe). However, at the flow rates corresponding to 75% THA and 50% THA, the discharge steam pressure of the intermediate-pressure cylinder is 0.444 MPa and 0.305 MPa, respectively, which is lower than 0.5 MPa. Adjusting this pressure through the regulating valve of the intermediate-low pressure cylinder connecting pipe is relatively difficult and insufficient to meet the heating demand. The discharge steam pressure of the first stage of the intermediate-pressure cylinder is 1.65 MPa and 1.11 MPa, respectively, which is higher than the industrial supply steam pressure. Heating can be provided through the discharge steam from the first stage of the intermediate-pressure cylinder, i.e., the first intermediate-pressure cylinder 3-4.

[0087] Table 1 Main parameters of the unit under pure condensing operation.

[0088]

[0089]

[0090] According to the system proposed in this invention, a high-pressure industrial steam supply condition analysis was conducted. Under 100% THA conditions, cold reheat steam was used for heating; under 75% THA and 50% THA conditions, exhaust steam from the first stage of the high-pressure cylinder was used for heating. The calculation results are summarized in Table 2. As shown in Table 2, under the main steam parameters corresponding to 100% THA operating conditions, when 100 t / h (3 MPa, 250℃) of steam is supplied via cold reheat steam, the unit's coal consumption for power generation is 222.2 g / kWh, and the ratio of power generation to nameplate power is 0.92. Under the main steam parameters corresponding to 75% THA operating conditions, when 100 t / h (3 MPa, 250℃) of steam is supplied via exhaust steam from the first stage of the high-pressure cylinder, the unit's coal consumption for power generation is 222.9 g / kWh, and the ratio of power generation to nameplate power is 0.67. Under the main steam parameters corresponding to 50% THA operating conditions, when 100 t / h (3 MPa, 250℃) of steam is supplied via exhaust steam from the first stage of the high-pressure cylinder, the unit's coal consumption for power generation is 240.1 g / kWh, and the ratio of power generation to nameplate power is 0.39.

[0091] The system performance analysis under high-pressure industrial steam supply conditions is as follows:

[0092] Table 2 Main parameters of the cogeneration unit of the present invention under the condition of meeting high-pressure industrial steam supply.

[0093]

[0094]

[0095] Table 3 summarizes the main performance indicators of the unit under the high-pressure cylinder stage 1 exhaust steam heating scheme and the conventional main steam desuperheating and pressure-reducing heating scheme of this invention. As can be seen from the table, under the main steam parameters corresponding to a pure condensing 75% THA condition, the coal consumption for power generation under the high-pressure cylinder stage 1 exhaust steam heating scheme of this invention is 222.2 g / kWh, while the coal consumption for power generation under the conventional main steam heating scheme is 287.3 g / kWh, representing a reduction of 65.1 g / kWh in coal consumption. Under the main steam parameters corresponding to a pure condensing 50% THA condition, the coal consumption for power generation under the high-pressure cylinder stage 1 exhaust steam heating scheme of this invention is 240.1 g / kWh, while the coal consumption for power generation under the conventional main steam heating scheme is 302.4 g / kWh, representing a reduction of 62.3 g / kWh in coal consumption. Through calculation and comparison, it can be concluded that the heating scheme proposed in this invention has significant coal-saving benefits.

[0096] Table 3 Comparison of the high-pressure cylinder stage 1 exhaust steam heating scheme and the conventional main steam heating scheme in this invention.

[0097]

[0098]

[0099] The system performance analysis under low-pressure industrial steam supply conditions is as follows:

[0100] Based on the proposed split-cylinder cogeneration system, a calculation and analysis of low-pressure heating conditions was performed. Under 100% THA conditions, heating was provided by exhaust steam from the second stage of the intermediate-pressure cylinder; under 75% THA and 50% THA conditions, heating was provided by exhaust steam from the first stage of the intermediate-pressure cylinder. The calculation results are summarized in Table 2. As shown in Table 2, under the main steam parameters corresponding to 100% THA operating conditions, when the steam supply through the intermediate pressure cylinder is 100 t / h (0.5 MPa, 200℃), the unit's coal consumption for power generation is 213.2 g / kWh; under the main steam parameters corresponding to 75% THA operating conditions, when the steam supply through the first stage of the intermediate pressure cylinder is 100 t / h (0.5 MPa, 200℃), the unit's coal consumption for power generation is 214.5 g / kWh; and under the main steam parameters corresponding to 50% THA operating conditions, when the steam supply through the first stage of the intermediate pressure cylinder is 100 t / h (0.5 MPa, 200℃), the unit's coal consumption for power generation is 221.7 g / kWh.

[0101] Table 4 Main parameters of the thermal system of this invention under the condition of low-pressure industrial steam supply

[0102]

[0103] Table 5 summarizes the main performance indicators of the unit under the medium-pressure cylinder stage 1 exhaust steam heating scheme and the conventional hot reheat steam desuperheating and pressure-reducing heating scheme of this invention. As can be seen from the table, under the main steam parameters corresponding to the 75% THA pure condensing condition, the coal consumption for power generation under the medium-pressure cylinder stage 1 exhaust steam heating scheme of this invention is 214.5 g / kWh, while the coal consumption for power generation under the conventional hot reheat steam heating scheme is 279.7 g / kWh, representing a reduction of 65.2 g / kWh in coal consumption. Under the main steam parameters corresponding to the 50% THA pure condensing condition, the coal consumption for power generation under the medium-pressure cylinder stage 1 exhaust steam heating scheme of this invention is 221.7 g / kWh, while the coal consumption for power generation under the conventional main steam heating scheme is 288.2 g / kWh, representing a reduction of 66.5 g / kWh in coal consumption. Through calculation and comparison, it can be concluded that the heating scheme proposed in this invention has significant coal-saving benefits.

[0104] Table 5 Comparison of the exhaust steam heating scheme of the first stage of the pressure cylinder in this invention with the conventional main steam heating scheme.

[0105]

[0106]

[0107] In summary, the high-pressure and medium-pressure cylinder heating system coupled with solar thermal energy proposed in this embodiment has the following advantages: (1) The furnace side uses solar thermal energy to replace part of the coal consumption; (2) Under low load conditions, compared with the main steam de-cooling and de-pressure heating, this scheme can achieve energy cascade utilization, energy saving and emission reduction. For a conventional 350MW ultra-supercritical unit, under the condition of high pressure steam supply, under the main steam parameters corresponding to the pure condensing 75% THA condition, the power generation coal consumption of the high-pressure cylinder 1-stage exhaust steam heating scheme proposed in this invention is reduced by 65.1g / kWh; under the condition of high and low pressure steam supply, under the main steam parameters corresponding to the pure condensing 50% THA condition, the power generation coal consumption of the medium-pressure cylinder 1-stage exhaust steam heating scheme proposed in this invention is reduced by 66.5g / kWh. (3) Compared with the limitation of the limited steam extraction capacity of the traditional regenerative system 1 extraction, this invention drills holes in the connecting pipe between the high-pressure cylinder 1-stage and 2-stage to extract steam, which significantly increases the extraction capacity and can meet the demand of 100t / h for high-pressure industrial steam supply extraction. In this invention, a high-efficiency cogeneration energy cascade utilization heating system based on high-pressure cylinder division consists of two-stage extraction steam sources: cold reheat steam and high-pressure cylinder section 1 exhaust steam. The heating steam source can be flexibly switched according to the unit's electrical load. (4) Compared with the limitation of the limited extraction steam volume of the traditional regenerative system with 3 extractions, this invention extracts steam by drilling holes in the connecting pipe between the 1st and 2nd sections of the intermediate-pressure cylinder, which significantly increases the extraction steam volume and can meet the demand of 100t / h for low-pressure industrial steam supply. In the heating system of this invention, there are two-stage extraction steam sources: intermediate-pressure cylinder exhaust steam and intermediate-pressure cylinder section 1 exhaust steam. The heating steam source can be flexibly switched according to the unit's electrical load.

[0108] Example 2

[0109] Figure 3 This is a flowchart illustrating a heating method using a high- and medium-pressure split-type cylinder coupled with solar thermal energy, according to an embodiment of this application. Figure 3 As shown, the method includes:

[0110] Step 1: Collect solar heat using a solar thermal power plant and transfer the heat to a molten salt heat exchange station;

[0111] Step 2: Based on the molten salt heat exchange station, and using the heat energy delivered by the solar thermal power plant, the cold resteam is heated to generate hot resteam, and then the hot resteam is delivered to the thermal power plant subsystem.

[0112] Step 3: The thermal power plant subsystem provides steam and electricity to users based on the heat resteam;

[0113] The thermal power plant subsystem includes: a boiler, a second high-pressure cylinder, a first high-pressure cylinder, a first intermediate-pressure cylinder, a second intermediate-pressure cylinder, a low-pressure cylinder, and a generator.

[0114] In summary, this embodiment proposes a heating method for high-pressure and medium-pressure cylinders coupled with solar thermal energy. This method involves separating the high-pressure and medium-pressure cylinders and combining them with solar energy to efficiently utilize solar thermal energy to replace part of the coal consumption in the boiler, thereby achieving energy conservation, emission reduction, and energy cascade utilization.

[0115] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0116] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0117] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A heating system with a high- and medium-pressure distribution cylinder coupled with solar thermal energy, characterized in that, include: Solar thermal power plants, molten salt heat exchange stations, and thermal power plant subsystems; The solar thermal power plant is used to collect solar heat and transport the heat to the molten salt heat exchange station; The molten salt heat exchange station is used to heat cold reheat steam to generate hot reheat steam, and then transport the hot reheat steam to the power plant subsystem. The thermal power plant subsystem is used to provide steam and electricity to users; The thermal power plant subsystem includes: a boiler, a second high-pressure cylinder, a first high-pressure cylinder, a first intermediate-pressure cylinder, a second intermediate-pressure cylinder, a low-pressure cylinder, and a generator, wherein the boiler, the second high-pressure cylinder, the first high-pressure cylinder, the first intermediate-pressure cylinder, the second intermediate-pressure cylinder, the low-pressure cylinder, and the generator are connected in sequence. A first connecting pipe is provided between the second high-pressure cylinder and the first high-pressure cylinder; A second connecting pipe is provided between the first intermediate pressure cylinder and the second intermediate pressure cylinder; A third connecting pipe is provided between the second intermediate-pressure cylinder and the low-pressure cylinder; The thermal power plant subsystem also includes: a high-pressure industrial steam supply main pipe and a medium-pressure industrial steam supply main pipe; The high-pressure industrial steam supply header is connected to the first connecting pipe and the outlet of the second high-pressure cylinder, respectively. The medium-pressure industrial steam supply main pipe is connected to the second connecting pipe and the third connecting pipe respectively; The thermal power plant subsystem also includes: multiple sealed butterfly valves; The high-pressure industrial steam supply main pipe is connected to the first connecting pipe and the outlet of the second high-pressure cylinder through the sealing butterfly valve. The medium-pressure industrial steam supply main pipe is connected to the second connecting pipe and the third connecting pipe respectively through a sealed butterfly valve; The sealing butterfly valve is installed between the input end of the molten salt heat exchange station and the output end of the second high-pressure cylinder.

2. The heating system of the high- and medium-pressure distribution cylinder as described in claim 1, characterized in that, The molten salt heat exchange station heats the cold reheat steam to generate hot reheat steam, and then delivers the hot reheat steam to the first intermediate pressure cylinder. The boiler is used to heat condensate to generate steam and deliver the steam to the first high-pressure cylinder.

3. The heating system of the high- and medium-pressure distribution cylinder as described in claim 2, characterized in that, When high-pressure steam is required, it is determined whether the unit load in the thermal power plant subsystem is less than a preset first load value. If so, the sealing butterfly valve connected to the first connecting pipe is opened, and the sealing butterfly valve connected to the second high-pressure cylinder is closed, using the extracted steam in the first high-pressure cylinder to provide high-pressure steam to the user; otherwise, the sealing butterfly valve connected to the second high-pressure cylinder is opened, and the sealing butterfly valve connected to the first connecting pipe is closed, using the cold re-extraction steam discharged from the second high-pressure cylinder to provide steam to the user. And / or, when medium-pressure steam or low-pressure steam is required, determine whether the unit load in the thermal power plant subsystem is less than a preset second load value. If so, open the sealing butterfly valve connected to the second connecting pipe and close the sealing butterfly valve connected to the third connecting pipe, and use the extracted steam in the first medium-pressure cylinder to provide medium-pressure steam or low-pressure steam to the user; otherwise, open the sealing butterfly valve connected to the third connecting pipe and close the sealing butterfly valve connected to the second connecting pipe, and use the cold re-extraction steam discharged from the second medium-pressure cylinder to provide medium-pressure steam or low-pressure steam to the user.

4. The heating system of the high- and medium-pressure distribution cylinder as described in claim 3, characterized in that, The thermal power plant subsystem also includes: condenser, condensate pump, and unit regenerative subsystem; The condenser is connected to the low-pressure cylinder, the condensate pump, and the unit's regenerative subsystem, respectively. The unit's regenerative subsystem is connected to the boiler, the second high-pressure cylinder, the first high-pressure cylinder, the first intermediate-pressure cylinder, the second intermediate-pressure cylinder, the low-pressure cylinder, the condenser, and the condensate pump, respectively.

5. The heating system of the high- and medium-pressure distribution cylinder as described in claim 1, characterized in that, The molten salt heat exchange station includes: a molten salt heat exchanger, a temperature gradient layer, and a main heat exchanger; The inclined temperature layer is connected to the molten salt heat exchanger; The molten salt heat exchanger is connected in parallel with the main heat exchanger.

6. The heating system of the high- and medium-pressure distribution cylinder as described in claim 1, characterized in that, The solar thermal power plant includes: heliostats and solar collector towers; The solar collector tower is connected to the molten salt heat exchange station.

7. A heating method for a high-pressure intermediate-pressure intermediate-pressure cylinder coupled with solar thermal energy in a heating system based on any one of claims 1-6, characterized in that, The method includes: Solar thermal power plants collect solar heat and then transfer the heat to molten salt heat exchange stations. Based on the molten salt heat exchange station, and using the heat energy delivered by the solar thermal power plant to heat the cold resteam to generate hot resteam, the hot resteam is then delivered to the thermal power plant subsystem. The thermal power plant subsystem provides steam and electricity to users based on the heat resteam.

Images